Applying LTTA to guarantee flow of data requirements in distributed systems using Controller Area Networks

Most automotive applications today consist of a set of interacting tasks. These applications are implemented on a distributed architecture consisting of several ECUs connected by buses. Although algorithms are designer to be robust, several communication flows between tasks should be designed in such a way that there is no loss of data. Furthermore, safety critical applications depend on correct data being delivered on time. We address this problem when the buses of the implementation architecture are Controller Area Networks (CANs). Flow-of-data requirements are addressed using an intermediate mapping solution where the LTTA protocol is used on some of the communication links. Then the problem becomes one of mapping LTTA links to CAN buses. We give conditions under which this mapping is feasible and show how to optimize the design solution with respect to performance.